Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$90.72	4.151%	$94.4858	$94.49	$94.50	$94.50
Purchase #2	$55.94	7.502%	$60.1366	$60.14	$60.15	$60.10
Purchase #3	$112.33	4.280%	$117.1377	$117.14	$117.15	$117.10
Purchase #4	$173.25	4.584%	$181.1918	$181.19	$181.20	$181.20
Purchase #5	$238.29	6.712%	$254.284	$254.28	$254.30	$254.30
Purchase #6	$46.65	3.233%	$48.1582	$48.16	$48.15	$48.20
Purchase #7	$246.40	11.844%	$275.5836	$275.58	$275.60	$275.60
7 purchase totals =	$963.58		$1,030.9777	$1,030.98	$1,031.05	$1,031.00